Finally got my RS Turbo running again but its not running right, basically it was ok, then i changed the Head Gasket, put on Cossie Turbo, new alternator, although due to other commitments the car was left in bits for about 6 weeks or so, put it all back together last night, and it just starts but is really lumpy and sounds like its gonna cut out just checked the timing and it seems ok, plugs seem to have carbon deposits on tips so will need changing but what coud cause it to run really lumpy? and how can i fix this